Mechanics

JEEP CJ7 GAUGES PROBLEM

1980 Jeep CJ7 • 280 miles

I'm going to remove the dash to chase a weak ground on my gas tank level. Does anyone have a drawing that shows where my heater, air, defroster cables are supoosed to go. They are incorrect and I want to fix them.
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Guest
March 13, 2013.



The heater grounds off of the motor and fuel gauge grounds to frame as well as tank sending unit. No drawing for cables but you mayhave one that ocnnects to heater under dash if you have two cables one will be for air direction (defrost heat) and the other will be for temperature. Sorry no pics


Hmac300
Mar 13, 2013.
OK ---BUDDY!

ARE YOU EXPERIENCED IN HOW THE SPEEDOMETER GAUGES WORK?

HAS YOU JEEP REMAINED PRETTY MUCH INTACT OVER THE YEARS, OR HAVE EVIL PEOPLE BEEN MAKING YOUR WIRING INTO A RAT'S NEST?

I CAN AID YOU IN CHECKING YOUR GAUGES AND SENDING UNIT OPERATION!

THE FUEL AND TEMP GAUGE ARE TIED TOGETHER

ALTHOUGH 12 VOLTS ENTERS IN TO THE FUEL GAUGEIT SORTA REDUCES IT DOWN TO ABOUT 5 VOLTS TO OPERATE BOTH GAUGES. THE FUEL GAUGE HAS THE "CVR" (CONSTANT VOLTAGE REGULATOR) BUILT INTO IT

THE "CVR" IS THE HEART OF THE OPERATION!

CONNECT THE 12 VOLTS TO THE WRONG TERMINAL AND YOU'LL BE BUYING ANOTHER SET OF GAUGES TO INSTALL. THEY DO GO BAD ON THEIR OWN. LET'S NOT ACCELERATE IT!

I CAN AID YOU WITH MOST ANY CJ ISSUE. YOU CAN KEEP ASKIN' ON THIS THREAD!

I DON'T MEAN TO BUT IN ON YOUR MISSION. BUT I'VE DONE THIS STUFF MANY TIMES. DON'T WANT YOU TO MESS UP

IN FACT, I JUST ORDERED 2 SET OF THE FUEL AND TEMP GAUGES MYSELF TO GET MY "PERTTY SPEEDOMETER" UP AND RUNNING AGAIN.I'M GETTING BY WITH MY OLD FADED ONE NOW

TELL ME WHAT WORKS---WHAT DON'T?

GOT A VOLTMETER AND A 12 VOLT TEST LIGHT?

WHAT YOU HAVE DONE THUS FAR.I NEED TO KNOW THE WHOLE DEAL, SO I CAN HELP YOU THE BEST-US!

GIVE ME THE WHOLE SPILL ON WHAT YOUR JEEP IS/ AND HAS IN IT

PICS ARE NICE----SOME WITH THE HOOD LAID BACK ON THE WINDSHIELD FRAME----AIR CLEANER OFF---IN BRIGHT DAYLIGHT (NOT REAL SUNNY)GIMME AN OVERHEAD VIEW STANDING ON THE BUMPER, AND EACH SIDE IN FULL

I REALLY GET INTO THIS STUFF. IN CASE YOU DIDN'T NOTICE

IF YOU'VE EXPLORED OUR CJ 5 AND 7 FORUMS, YOU WILL SEE I TRY TO GRAB 'EM ALL, WHEN ONE FINALLY BREAKS

OK---IT'S YOUR TURN. THE LAST 3 THAT CAME ABOARD HAVE NEVER RESPONDED TO ME. MAKES ME SAD!

FOR SOME REASON WHEN YOU CLICK ON THE PICS, THEY ARE NOT ENLARGING---THEY MUST BE DOING SOME SORTA MAINTENANCE TO 2CAR. COME BACK LATER AND CLICK THEM SO YOU CAN SEE THE WHOLE PIC

THE MEDIC


Tiny
CJ MEDEVAC
Mar 13, 2013.
Both gauges work. Temp works well. Fuel gauge reads almost full when the tank is full but rapidly goes to empty over the next 8 miles. This is very repeatable. I will have to check my notes, but the sending unit has the correct resistances. I think the ground coming off my fuel meter may have some resistance of it's own. I'll try to get some pictures of the engine bay tomorrow. I'm stuck at the plant again, another outage. The heater core got changed a couple of years back and the cables have not been right since.


Tiny
Rikphred
Mar 16, 2013.
I AM NOT GETTING NOTIFICATIONS OF ACTIVITY ON POSTS I'VE ANSWERED

I RECKON THAT'S WHY THE OTHER CJs AIN'T SHOWED UP.I RECKON I NEED TO HUNT THEM DOWN TOO!

HOW ARE YOU TESTING THE SENDER RESISTANCES. DID YOU DO IT WITH THE TANK OUT?

I HAVE PLENTY OF INFO FOR YOU. GOTTA DO A HONEY--DO RIGHT NOW, SHE DON'T LIKE TO WAIT.I'M SORTA WITHIN SLAPPING DISTANCE!

THE MEDIC


Tiny
CJ MEDEVAC
Mar 16, 2013.
YOU MAY BE HAVING SIMILAR PROBLEMS TO ME

I HAVE FOUND THAT THERE ARE 2 DIFFERENT STYLES OF CLUSTERS---THE 1ST WHICH IS THE OEM, THE FUEL GAUGE HAS A RECTANGULAR CUT OUT BEHIND IT.'CEPT THE RECTANGLE HAS A DIVISION DOWN THE MIDDLE OF IT, MAKING IT "2 SIDE-BY-SIDE SQUARES"

THE CVR GROUNDS TO THIS "DIVIDING BAR" (THE COPPER STRIP ON THE BACK OF THE FUEL GAUGE

I'VE HAD ISSUES IN THE PAST OF THAT CONNECTION. NOT GROUNDING WELL

A "LITTLE SCRATCHING" ON THE "BAR" AND ON THE COPPER BAND, THAT IS CENTERED ON THE BACK OF THE FUEL GAUGE WITH SOME FINE SAND PAPER WORKS WELL FOR MAKING A GOOD CONTACT

NOW THEN--KINDA MY 1ST ENCOUNTER WITH "FIXIN" AN AFTER-MARKET CLUSTER

YEARS AGO I BOUGHT AN AFTER-MARKET CLUSTER, CAUSE MY ORIGINAL FACES AND NEEDLES WERE FADING. AND.I GOT A HECK OF A DEAL ON IT. $60

I INSTALLED IT AND HAD NO PROBLEMS TILL ABOUT A YEAR AGO

I'VE REPLACED THE FUEL AND TEMP GAUGES IN MY ORIGINAL CLUSTERS AND FOR OTHER FOLKS, IN THEIRS

THIS WAS MY 1ST ENCOUNTER W/ CHANGING THEM IN AN AFTER-MARKET ONE, THEY SORTA SAID THE FUEL AND TEMP GAUGES WERE "IMPROVED" OVER THE OEM.I TAKE THAT TO MEAN "BETTER"

WITHOUT AN ORIGINAL CLUSTER ON THE TABLE, I INSTALLED THE GAUGES IN THE AFTER-MARKET ONE, WHEN INSTALLED BACK IN MY JEEP I NOTICED THEY FLUCTUATED UP AND DOWN---AND WHEN THEY SOMETIMES SETTLED DOWN, THEY WOULD MOVE MAYBE 2 NEEDLE WIDTHS BACK AND FORTH----SITTING STILL--OR ON THE ROAD

I THOUGHT I HAD FRIED THEM SOMEHOW OR ANOTHER (I REALLY DIDN'T THINK I DID!)---SO I ORDERED ANOTHER SET ANYWAY. SAME RESULTS?

I INSTALLED MY ORIGINAL CLUSTER BACK IN AND HAVE BEEN USING IT EVER SINCE

I SENT ALL 4 GAUGES BACK FOR REPLACEMENTS RECENTLY.I AM PRESENTLY WAITING FOR 4 NEW ONES TO ARRIVE BACK

. BUT

ABOUT A MONTH AGO, I PULLED OUT THE AFTER-MARKET ONE (THE PERTTY ONE) AND TORE INTO IT ONCE AGAIN, THIS TIME I REALIZED THAT BEHIND THE FUEL GAUGE ON THE BACK OF THE CLUSTER WAS THAT "RECTANGLE" AND IT WAS A FULL RECTANGLE WITH "NO" DIVISION BAR SEPARATING IT INTO TWO SQUARES

SO NOW, THAT I THREW THE BAD GAUGES OUT, AND NO NEW ONES YET.I'M WONDERING HOW THE CVR GETS GROUNDED WITHOUT "THE BAR" IN THE MIDDLE?

YEAH.I KNOW I'M THE ONE THAT'S SUPPOSED TO KNOW.I WILL, SOON AS I GET THE NEW ONES BACK!

AS FAR AS WHAT YOU INITIALLY ASKEDYOU MEAN THE CABLES THAT ARE CONTROLLING THE HEATER/ AIR FUNCTIONS ON THE HEATER BOX FROM THE DASH?

EXPLAIN ZACKLY WHAT YOU HAVE. YOU INSTALLED THE HEATER. IT WAS A BASKET CASE?

THE 1979 ON UP HEATER IS SIMPLE TO UNDERSTAND, TILL YOU GET TO THE CABLE THAT CONTROLS THE HEAT/ AIR. MOST CJ PEOPLE DON'T EVEN UNDERSTAND HOW TO CORRECTLY ENGAGE THE HEAT (FOR 100% HEAT) AND HOW TO USE THE "AIR" (100% AIR FROM THE HOOD VENT--NO BLOWER USED) WHICH COOLS THE PASSENGER SIDE AND BLOWS AIR BETWEEN THE DRIVER'S LEGS)

AS FAR AS "BATTERY GROUND" THE NEGATIVE CABLE SHOULD GO TO THE ENGINE BLOCK----A BRAIDED STRAP JUMPS AROUND THE MOTOR MOUNT AND FROM THE BRACKET AND GROUNDS TO THE FRAME.

OFF OF THE NEGATIVE BATTERY CLAMP, A HEAVY WIRE GROUNDS TO THE FIREWALL TO GROUND THE BODY

THE FUEL TANK SENDING UNIT (THE WHOLE ROUND DEALEE IN THE TOP) GROUNDS TO THE FRAMEWORK ABOVE IT. SEE THE BLACK WIRE IN THE 1ST PIC DANGLING OFF LEFT AND DOWN

. THIS IS A PIC FROM SOMEONE ELSE'S JEEP---DISREGARD THEIR "PLUGGING OFF" OF THE VENTS ON THE LEFT SIDE BY HOOKING A HOSE AROUND TO THE OTHER SIDETHIS IS NOT GOOD, IT SHOULD ATTACH TO THE "LIQUID CHECK" AND "ROLL-OVER" CHECK VALVES BEHIND THE DRIVER'S SIDE REAR WHEEL

. THE SENDER WIRE ORIGINATES IN THE CENTER OF THE "ROUND DEALEE" (SEE RIGHT SIDE OF MY 2ND PIC) THE "L" SHAPED RUBBER CONNECTOR IS THE BEGINNING OF THE "PINK" SENDER WIRE

IT TRAVELS ABOUT 2 FEET AND HITS A CONNECTOR (FOR TANK REMOVAL OR FOR TESTING) THIS CONNECTOR IS BETWEEN THE TANK AND BACK OF THE REAR TIRE ON THE DRIVER'S SIDE (I COULD NOT FIND MY PIC) THE WIRE IS PINK

THIS WIRE GOES ITO A CONNECTOR WITH THE OTHER WIRES FOR THE BACK

THE BUNDLE TRAVELS UNDER THE LIP OF THE SIDE OF THE JEEP AND COMES OUT UNDER THE DASH ON THE DRIVER'S SIDE

AS YOU CAN SEE----THE ONLY GROUNDS FOR THE GAUGE IS "THE GAUGE BODY ITSELF" AND THE "CVR DEALEE ON THE BACK OF THE FUEL GAUGE (INSIDE THE CLUSTER) AGAINST THE "BAR DEALEE" WHICH IS THE METAL OF THE SPEEDOMETER CASE

SORTA TO SHOW YOU THE EXTENT I GO TO INSURE MY STUFF WORKS RIGHT, EVEN TWEAKING THE FLOAT ARM TO MAKE THE GAUGE ACTUALLY READ "E" WHEN IT'S EMPTY

I HAVE FOUND MOST OF THE TIME, THE SENDERS DO NOT READ PERFECT

I DON'T REALLY CARE IF I READ "FULL" OR "OVER FULL"FOR THE 1ST 100 MILES, THEN IT DROPS THRU THE RANGE OVER THE NEXT 100+ MILES.I WANNA KNOW WHEN IT'S GETTING CLOSE TO "WALKING TIME!". THAT'S WHAT I TWEAK TOWARDS, BEFORE I INSTALL THE SENDER IN THE TANK.I RUN IT THRU THE MOTIONS USING JUMPER WIRES WITH ALLIGATOR CLIPS, HOOKED TO MY GAUGE

I REALLY DON'T WORRY TOO MUCH----SINCE I INSTALLED THE HOLLEY 390 4 BBL AND JETTED/ TUNED AND ADJUSTED IT ON MY 258 INLINE 6 CYLINDER.I GET ABOUT 18 MPG, I HAVE A 21 GALLON POLYETHYLENE FUEL TANK, AND MY 5 GALLON JERRY CAN IS ALWAYS FULL ON THE BACK!

IF YOU WANT MY FULL COLORED 1979 WIRE DIAGRAM I DID IN "MICROSOFT PAINT" (2 HALF PIECES) WHICH I BLEW UP AND LAMINATED. LET ME KNOW

IF YOU TAKE THE CONNECTOR LOOSE BEHIND/ BETWEEN THE DRIVER'S REAR TIRE AND TANK

. THEN

GROUNDING THE PINK SENDER WIRE TO THE BODY/ FRAME/ NEG SIDE OF THE BATTERYWILL MAKE THE FUEL GAUGE RISE TO THE TOP----IT SHOULD FALL TO NOTHIN' WHEN YOU TAKE THE GROUND AWAY

I HAVE MORE IN DEPTH TESTING PROCEDURES FOR THE GAUGES----THEY ARE REALLY GOOD!--LET ME KNOW IF YOU NEED THEM

HOPE YOU CAN UNDERSTAND MY HILLBILLY ANSWERING---THROWIN' SOME PICS OF MY QUESTS FOR PERFECTION. SEE.I REALLY GET INTO THIS, AND WRITE NOVELS FOR ANSWERS

YOUR TURN

THE MEDIC


Tiny
CJ MEDEVAC
Mar 17, 2013.
SITE JUST AIN'T COOPERATING---HAD MORE PICS--I TRY AGAIN

THE ONE THAT SHOULDA BEEN 2ND ABOVE---IS NOW THE LAST ONE


Tiny
CJ MEDEVAC
Mar 17, 2013.